Multiferroicity in atomic van der Waals heterostructures

Abstract

Materials that are simultaneously ferromagnetic and ferroelectric – multiferroics – promise the control of disparate ferroic orders, leading to technological advances in microwave magnetoelectric applications and next generation of spintronics. Single-phase multiferroics are challenged by the opposite d-orbital occupations imposed by the two ferroics, and heterogeneous nanocomposite multiferroics demand ingredients’ structural compatibility with the resultant multiferroicity exclusively at inter-materials boundaries. Here we propose the two-dimensional heterostructure multiferroics by stacking up atomic layers of ferromagnetic Cr<inf>2</inf>Ge<inf>2</inf>Te<inf>6</inf> and ferroelectric In<inf>2</inf>Se<inf>3</inf>, thereby leading to all-atomic multiferroicity. Through first-principles density functional theory calculations, we find as In<inf>2</inf>Se<inf>3</inf> reverses its polarization, the magnetism of Cr<inf>2</inf>Ge<inf>2</inf>Te<inf>6</inf> is switched, and correspondingly In<inf>2</inf>Se<inf>3</inf> becomes a switchable magnetic semiconductor due to proximity effect. This unprecedented multiferroic duality (i.e., switchable ferromagnet and switchable magnetic semiconductor) enables both layers for logic applications. Van der Waals heterostructure multiferroics open the door for exploring the low-dimensional magnetoelectric physics and spintronic applications based on artificial superlattices.